Re: the joy of breaking out from procedural/imperative programming style (was: Re: [xsl] Peculiar Problem in .xsl file

["Kurt Cagle" <cagle@xxxxxxxxx>]

Gunther,

Things get even better in XSLT2/Xpath2
<xsl:stylesheet ...  xmlns:dt="http://www.mySchemas.com/date";>
<xsl:function name=" dt:getMonthName"
xmlns:dt="http://www.mySchemas.com/date";>
    <xsl:param name="date"/>
    <xsl:variable name="months"
select="tokenize("January,February,March,April,May,June,July,August,Septembe
r,October,November,December",',')"/>
    <xsl:return select="$months[number(substring($monthNum,5,2))]"/>
</xsl:function>
...
<xsl:value-of select="dt:getMonthName(current-dateTime())"/>
...
</xsl:stylesheet>

Functional Programming at its most basic.


----- Original Message -----
From: "Gunther Schadow" <gunther@xxxxxxxxxxxxxxxxxxxxxx>
To: <xsl-list@xxxxxxxxxxxxxxxxxxxxxx>; "Chandra -"
<pchandramohan@xxxxxxxxxxx>
Sent: Friday, December 06, 2002 8:31 AM
Subject: the joy of breaking out from procedural/imperative programming
style (was: Re: [xsl] Peculiar Problem in .xsl file


> Hi, on Chandra's issue of month names, etc. I'd like to take
> the oportunity to do some XSLT style-evangelism.
>
> I think this case is a particular good example for how ugly
> choices are and that one should deliberately try to find other
> ways than using xsl:choose, (and xsl:call-template, xsl:for-each
> for that matter.)
>
> XSLT is much more fun if you use its own powers rather than
> trying to cling on to the weak metaphors of imperative programming
> (i.e., case, procedure call and loops.)
>
> So, instead of this ugly choice, you could make tables:
>
> <xsl:variable name="monthNames">
>    <month digits="01" name="January"/>
>    <month digits="02" name="February"/>
>    <month digits="03" name="March"/>
>    <month digits="04" name="April"/>
>    <month digits="05" name="May"/>
>    <month digits="06" name="June"/>
>    <month digits="07" name="July"/>
>    <month digits="08" name="August"/>
>    <month digits="09" name="September"/>
>    <month digits="10" name="October"/>
>    <month digits="11" name="November"/>
>    <month digits="12" name="December"/>
> <xsl:variable>
>
> and then you simply go:
>
> <xsl:value-of
>    select="$monthNames/month[@digits=substring($date, 5, 2)]/@name"/>
>
> just think of relational model for most of your data, the above
> is same as the SQL form
>
>    SELECT name FROM monthNames WHERE digits='..'
>
> The advantage: much cleaner code, much less ugly choose/when,
> easily reuseable, easily EXTENSIBLE. For instance you could
> easily support multi-lingual date representations either by
> loading the month name table from an external resource:
>
> <xsl:variable name="monthNames" select="document($monthnamesuri)"/>
>
> or by adding another "column" for language code such as:
>
>    <month digits="01" name="January" xml:lang="en"/>
>    <month digits="01" name="Januar" xml:lang="dn"/>
>    <month digits="01" name="Janvier" xml:lang="fr"/>
>
> etc.
>
> Just indulge in the many possible ways you could read this data
> from XML locale files.
>
> XSLT is so much fun if you can break out of the imperative/
> procedural progamming box. (And much pain and suffering if you
> don't break out of that box.)
>
> enjoy,
> -Gunther
>
>
> Gunther Schadow wrote:
>
> > What you should try is this:
> >
> > <xsl:when test="$month='01'">
> >
> > instead of <xsl:when test="$month=01">
> >
> > that way you avoid the potentially buggy type casting behavior
> > of your XSLT processor to become manifest. Just leave the values
> > you compare both strings at all times (it's probably slightly
> > faster that way anyway :-). That way you are sure to hold on to
> > the leading zero.
> >
> > In fact I wonder if it's really buggy type casting? It seem to
> > be reasonable for this machinery to cast the second operand to
> > of the = relation to the data type of the first operand. That
> > would cast the number 1 to a string, which would be '1', then
> > you compare '01'='1' and the answer is correctly false. XSLT
> > spec might make a ruling that clarifies that, but it's a subtle
> > problem, so, I'd expect that to go wrong somewhere. Luckily
> > your workaround is straight-forward.
> >
> > regards,
> > -Gunther
> >
> >
> > Chandra - wrote:
> >
> >> Hi Guys,
> >>  I am trying to print out a html file with a date in words, given date
> >> in a xml file in number format
> >> XSL file:
> >> <xsl:variable name='month' select='substring ($date, 5, 2)'/>
> >>     <xsl:choose>
> >>         <xsl:when test='$month=01'>
> >>             <xsl:text>January </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=02'>
> >>             <xsl:text>February </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=03'>
> >>             <xsl:text>March </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=04'>
> >>             <xsl:text>April </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=05'>
> >>             <xsl:text>May </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=06'>
> >>             <xsl:text>June </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=07'>
> >>             <xsl:text>July </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=08'>
> >>             <xsl:text>August </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=09'>
> >>             <xsl:text>September </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=10'>
> >>             <xsl:text>October </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=11'>
> >>             <xsl:text>November </xsl:text>
> >>         </xsl:when>
> >>         <xsl:when test='$month=12'>
> >>             <xsl:text>December </xsl:text>
> >>         </xsl:when>
> >>     </xsl:choose>
> >>
> >> When valuepassed into the date variable is 20020516, I don't get a
> >> month. Infact if the month is from 01 to 09, I dont get a month in
> >> words. If the month is 10 to 12, I get a month displayed. Very very
> >> peculiar. I am unable to find the solution. I tried and printed out
> >> the value of the month variable. It seems to take the 2 digits
> >> correctly. However it doesn't go into the appropraite month code when
> >> the month starts with 0!! For example, if the month is 05, it doesnt
> >> go into this part of the code:
> >> <xsl:when test='$month=05'>
> >> <xsl:text>May </xsl:text>
> >> </xsl:when>
> >> If the month were 10, 11 or 12, the code works fine.
> >> Can anyone guess what the problem is...
> >> Thanks in advance,
> >> Chandra
> >>
> >>
> >>
> >> _________________________________________________________________
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> >>
> >> XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list
> >
> >
> >
>
>
> --
> Gunther Schadow, M.D., Ph.D.                    gschadow@xxxxxxxxxxxxxxx
> Medical Information Scientist      Regenstrief Institute for Health Care
> Adjunct Assistant Professor        Indiana University School of Medicine
> tel:1(317)630-7960                         http://aurora.regenstrief.org
>
>
>
>  XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list
>
>


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